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Fatima Rout
Asked: 2022-11-04T05:26:44+05:30 In:

`152(sin30^(@)+2cos^(@)45^(@)+3sin30^(@)+4cos2^(2)45+ . . . .+17sin30^(@)+18cos^(2)45^(@)` का मान क्या होगा?
A. An interger but not perfect square
B. a rational number but not an interger
C. a perfect square of an integer
D. irrational

`152(sin30^(@)+2cos^(@)45^(@)+3sin30^(@)+4cos2^(2)45+ . . . .+17sin30^(@)+18cos^(2)45^(@)` का मान क्या होगा?
A. An interger but not perfect square
B. a rational number but not an interger
C. a perfect square of an integer
D. irrational
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  1. Correct Answer – c
    `152(sin30^(@)+2cos^(2)45^(@)+3sin30^(@)………+17sin30^(@)+18cos^(2)45^(@))`
    `=152[(1)/(2)+2((1)/sqrt(2))^(2)+3xx(1)/(2)……..17xx(1)/(2)+18((1)/sqrt(2))^(2)]`
    `rArr 152[(1)/(2)+1+1(1)/(2)+………..+ 8(1)/(2)+9]`
    `rArr` This is in A.P. where `a=(1)/(2),d=(1)/(2),n= 18`
    `rArr 15 2[(18)/(2)(2xx(1) /(2)+(18-1)(1)/(2))]`
    `rArr 152 [(18)/(2)(1+(17)/(2))]`
    `rArr 152xx9xx(19)/(2)rArr12996`
    `rarrsqrt(12996)`
    =114

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